/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package datafu.hourglass.test.jobs.counting;

import java.io.Serializable;

import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;

import datafu.hourglass.model.Accumulator;

public class CountAccumulator implements Accumulator<GenericRecord,GenericRecord>, Serializable
{  
  private long count = 0L;
  private transient GenericRecord output;
  private String schema;
  
  public CountAccumulator(Schema valueSchema)
  {
    schema = valueSchema.toString();
  }
  
  @Override
  public void accumulate(GenericRecord value)
  {
    count += (Long)value.get("count");
  }
  
  private void init()
  {
    if (output == null)
    {
      output = new GenericData.Record(new Schema.Parser().parse(schema));
    }
  }

  @Override
  public GenericRecord getFinal()
  {
    init();
    if (count > 0)
    {
      output.put("count", count);
      return output;
    }
    else
    {
      return null;
    }
  }

  @Override
  public void cleanup()
  {
    this.count = 0L;
  }
}